96 grand am 2.4 losing power when driving

I have a 96 GT 2.4 and it has a problem when driving. It will act like it wants to die when running around 2 grand. I will usually do it more often when its just started but it will also do it after running awhile. I either acts like its flooding or getting no gas. it idles smooth as can be. I replaced the fuel filter, coil tower and ignition module, spark plugs and boots, and o2 sensor. The trouble codes that come up are p0141 and p0134 and this is after i replaced the 02 sensor and cleared the codes. Any help would be very much appreciated. :banghead:

I forgot to add that if it starts acting up and you step on the gas down it will ga oway.